May 30, 2012

John R. Brophy Jet Propulsion Laboratory California Institute of Technology, Pasadena, CA

Lou Friedman The Planetary Society Pasadena, CA

Fred Culick California Institute of Technology, Pasadena, CA Study C0-Leads: John Brophy (JPL) Lou Friedman (The Planetary Society) Fred Culick (Caltech)

 Carl Allen (NASA JSC)  John Lewis (University of Arizona)  David Baughman (Naval Postgraduate School)  Pedro Llanos (USC)  Julie Bellerose (NASA ARC)  Mark Lupisella (NASA GSFC)  Bruce Betts (The Planetary Society)  Dan Mazanek (NASA LaRC)  Mike Brown (Caltech)  Prakhar Mehrotra (Caltech)  Michael Busch (UCLA)  Joe Nuth (NASA GSFC)  John Casani (NASA JPL)  Kevin Parkin (NASA ARC)  Marcello Coradini (ESA)  Rusty Schweickart (B612 Foundation)  John Dankanich(NASA GRC)  Guru Singh (NASA JPL)  Paul Dimotakis (Caltech)  Nathan Strange (NASA JPL)  Martin Elvis (Harvard-Smithsonian Center for  Marco Tantardini (The Planetary Society) Astrophysics)  Brian Wilcox (NASA JPL)  Ian Garrick-Bethell (UCSC)  Colin Williams (NASA JPL)  Robert Gershman (NASA JPL)  Willie Williams (NASA JSC)  Tom Jones (Florida Institute for Human and  Don Yeomans (NASA JPL) Machine Cognition)  Damon Landau (NASA JPL)  Chris Lewicki (ArkydAstronautics) Two Workshops – Sep 2011, Feb 2012 2  Determine the feasibility of robotically capturing and returning a small near-Earth asteroid to the vicinity of the Earth using technology available in this decade.

 Identify the benefits to NASA, the scientific community, the aerospace community, and the general public of such an endeavor.

 Identify how this endeavor could impact NASA’s and the international space community’s plans for human exploration beyond low-Earth orbit.

3 The idea to exploit the natural resources of asteroids is older than the space program.

 In 1903 “exploitation of asteroids” was one of Tsiolkovskii’s fourteen points for the conquest of space.

 In 1996, detailed in John Lewis’ book Mining the Sky

 It has long been a major theme of science fiction stories.

4 This is the exactly the right time to investigate the feasibility of this mission. 1. The capability for discovering and characterizing sufficiently small NEAs is just becoming available . 2. Sufficiently large solar electric propulsion systems required to transport the NEAs are just becoming available. 3. The human spaceflight activity is planning for a crewed exploration capability in cislunar space in the 2020’s.

5 The Apollo program returned 382 kg of moon rocks in six missions. The OSIRIS-REx mission will return at least 60 grams of surface material from a NEA by 2023.

We evaluated the OSIRIS-REx feasibility returning an entire ~7-m dia. near-Earth asteroid, with a mass of order 500,000 kg, to a high lunar orbit, by 2026.

6  Placing a 500-t asteroid in high lunar orbit would provide a unique, meaningful, destination for astronaut crews in the next decade.

 It would provide a high-value target in cislunar space that would require a human presence to take full advantage of this new resource.

 It would offer an affordable path to providing operational experience with astronauts working around and with a NEA that could feed forward to much longer duration human missions to larger NEAs in deep space.

 Robotic spacecraft retrieval of significant quantities of valuable resources could be exploited by astronaut crews to enable human exploration farther out into the solar system.

 The capture, transportation, examination, and dissection of an entire NEA would provide valuable information for planetary defense activities. 7 The International Space Station has a mass of about 450,000 kg

3 Most NEAs have densities between 1.9 and 3.8 g/cm 8 21 ½ foot, 340-ton boulder selected by artist Michael Heizer as the centerpiece of his latest creation 'Levitated Mass.' (AP Photo/The Press-Enterprise, Mark Zaleski, File) 9  Discovery & Characterization

 Capture

 Transportation

10  Need to identify sufficient candidates around which a mission can be planed for a launch around 2020.  Larger asteroids easier to discover and characterize but much harder to move.  Volume and mass scale as the cube of the diameter, projected area (and brightness) scales as the square of the diameter

 Determine the overlap between NEAs large enough to be discovered and characterized and those small enough to be moved. For each candidate target asteroid need to know:  orbit  spectral type Want a C-Type Carbonaceous  size Chondrite Asteroid:  shape • Up to 40% volatiles (water,  spin state CO2, N2, NH3, etc.)  mass  synodic period 11 12  Generally people haven’t been  Observation Campaign interested in very small asteroids  Both Pan-STARRS and Palomar  280 NEAs ~10-m diameter Transient Factory (PTF) automatically discovered to date reject fast-moving objects  Step 1: modify pipelines to report such  Few have secure orbits, none have detections known spectral types  Step 2: Screen for follow-up observations which must be made in a New Telescopes matter of hours or days  PanSTARRS 1 on Haleakala in Maui  Step 3: Follow-up observations will be about 6.5 time better than the • Optical lightcurve current SOA. • Spectroscopy (optical and near-IR) • Radar imaging  PanSTARRS 4 will be about 26 times better. Pan-STARRS  The Large Synoptic Survey Telescope (LSST), which will be a 8.4 meter aperture wide field telescope in Chile that hopes for first light in 2018. The LSST will be ~150 times more efficient at finding NEOs.

13 The Panoramic Survey Telescope & Rapid Response System  Thermal infrared flux measurements for object’s albedo  For small objects dimensions are only accurate to ~30-40%

 Radar ranging measurements to determine orbit and dimensions  Goldstone Radar can image asteroids with 3.75-m resolution (expected to improve to 2-m resolution)

 Radar and composition information can reduce asteroid mass uncertainty to a factor of 4 for most objects

14 Time Since Rate Follow-Up Observation Discovery (#/day)

< 12 hrs 10 Astrometry

< 24 hrs 0.5 Additional astrometry, colors

< 48 hrs 0.2 Lightcurves (spin rate)

< 48 hrs 0.1 Spectroscopy (type)

< 72 hrs 0.06 Radar (orbit, size, spin)

• >3,500 new discoveries per year • Yield: ~5 good targets per year (right size, type, spin state, and orbital characteristics)

15 Belt and Suspenders approach to safety  A 7-m diameter asteroid is too small to be considered a potentially hazardous object (PHO)  Carbonaceous asteroids are expected to have the strength of “dried mud” and will breakup harmlessly in the Earth’s atmosphere  The spacecraft will keep the asteroid on a non-collision course with Earth at all times  The final destination is a high lunar orbit

16 40-kW SEP System

17 Launch Configuration Outbound Transit Asteroid Capture Bag Configuration Deployed

Asteroid Capture Configuration

Inbound Transit Configuration 18 4 Pods of 4 Roll 5 Total Hall Control Thrusters and Thrusters Gimbals

Hall Thruster and Gimbal

Roll Control Thruster

19 Stowed Inflatable Crushable Asteroid Capture Foam For Bag Asteroid “Landing” Radiator Radiator

Ka-Band Bag Reflect Array, Deployment TWT, EPC, and Camera and 2 Radiator 10.7 meter X-Band Bag Ultraflex Solar Antennas Deployment Camera Array 10.7 meter Ultraflex Solar Array 20 Guidance Camera (4 Science Total) Camera (4 Total)

Science NIR Science LIDAR Spectrometer (2 Total) (2 Total)

Crushable Stowed Inflatable Foam For Asteroid Capture Asteroid Bag “Landing”

21 10-kW Hall Thruster  40-kW EOL solar array  Two wings of 71 m2 each  Five 10-kW Hall thrusters  Isp = 3,000 s  Multiple cylindrical COPV xenon tanks to store 12,000 kg of xenon  650 mm dia. x 3,500 mm long  Inflatable, rigidizable capture mechanism with high- strength bag and cinching capbles

22 23 Mass Estimate Cost Estimate

Launch vehicle capability to LEO: 18,800 kg

24 25  Initial Launch Mass: 18,000 kg

 Return Mass 1,300,000 kg

 Total Flight Time 10 years

 Mass Amplification 70-to-1

26 Mass launched to Low-Earth Orbit

Launch mass reduced to a single EELV

27 A C-type asteroid is may have up to 40% of extractable volatile material and about 18% metals A 1000 metric ton C-type asteroid may contain  400 t of volatiles (water, carbon dioxide, nitrogen, ammonia, etc.)  180 t of metals (roughly 170 t of iron, 13 t of nickel, 2 t of cobalt)  400 t of other stuff.

28  Robotic SEP is enabling for this mission concept

 This mission concept requires a human crew in cislunar space to “process” the 500,000 kg asteroid

 This represents a new synergy between robotic and human missions

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